Re: [RFC/RFA] find_pc_sect_psymtab(): symbol table not always complete

Elena Zannoni
2004-02-19T19:01:26Z

Joel Brobecker writes:

Joel, I committed an updated version of your patch. By updated I mean
with new/more comments. Now let's keep an eye on any apparently
unrelated breakage :-)

elena

2004-02-19 Joel Brobecker <brobecker@gnat.com>

Committed by Elena Zannoni <ezannoni@redhat.com>
* symtab.c (find_pc_sect_psymtab): Return the psymtab that
contains a symbol wich is the best, non-exact match for the given
pc. Update comments.

Index: symtab.c
===================================================================
RCS file: /cvs/src/src/gdb/symtab.c,v
retrieving revision 1.127
diff -u -p -r1.127 symtab.c
--- symtab.c 17 Feb 2004 15:21:22 -0000 1.127
+++ symtab.c 19 Feb 2004 17:13:11 -0000
@@ -672,8 +672,10 @@ init_sal (struct symtab_and_line *sal)

-/* Find which partial symtab on contains PC and SECTION. Return 0 if none. */-
+/* Find which partial symtab contains PC and SECTION. Return 0 if
+ none. We return the psymtab that contains a symbol whose address
+ exactly matches PC, or, if we cannot find an exact match, the
+ psymtab that contains a symbol whose address is closest to PC. */
struct partial_symtab *
find_pc_sect_psymtab (CORE_ADDR pc, asection *section)
{
@@ -698,6 +700,8 @@ find_pc_sect_psymtab (CORE_ADDR pc, asec
if (pc >= pst->textlow && pc < pst->texthigh)
{
struct partial_symtab *tpst;
+ struct partial_symtab *best_pst = pst;
+ struct partial_symbol *best_psym = NULL;

/* An objfile that has its functions reordered might have
many partial symbol tables containing the PC, but
@@ -710,6 +714,13 @@ find_pc_sect_psymtab (CORE_ADDR pc, asec
if (msymbol == NULL)
return (pst);

+ /* The code range of partial symtabs sometimes overlap, so, in
+ the loop below, we need to check all partial symtabs and
+ find the one that fits better for the given PC address. We
+ select the partial symtab that contains a symbol whose
+ address is closest to the PC address. By closest we mean
+ that find_pc_sect_symbol returns the symbol with address
+ that is closest and still less than the given PC. */
for (tpst = pst; tpst != NULL; tpst = tpst->next)
{
if (pc >= tpst->textlow && pc < tpst->texthigh)
@@ -721,9 +732,33 @@ find_pc_sect_psymtab (CORE_ADDR pc, asec
&& SYMBOL_VALUE_ADDRESS (p)
== SYMBOL_VALUE_ADDRESS (msymbol))
return (tpst);
+ if (p != NULL)
+ {
+ /* We found a symbol in this partial symtab which
+ matches (or is closest to) PC, check whether it
+ is closer than our current BEST_PSYM. Since
+ this symbol address is necessarily lower or
+ equal to PC, the symbol closer to PC is the
+ symbol which address is the highest. */
+ /* This way we return the psymtab which contains
+ such best match symbol. This can help in cases
+ where the symbol information/debuginfo is not
+ complete, like for instance on IRIX6 with gcc,
+ where no debug info is emitted for
+ statics. (See also the nodebug.exp
+ testcase.) */
+ if (best_psym == NULL
+ || SYMBOL_VALUE_ADDRESS (p)
+ > SYMBOL_VALUE_ADDRESS (best_psym))
+ {
+ best_psym = p;
+ best_pst = tpst;
+ }
+ }
+
}
}
- return (pst);
+ return (best_pst);
}
}
return (NULL);